In reply to girlymonkey:
Radio 4 this morning had a programme about autism (well, an interview with Simon Baron-Cohen: 'One To One' 9:30-9.45am), of which I caught a couple of minutes [now listened to it all on iPlayer; short, but quite interesting]. But it reminded me that introversion seems to be associated with autistic spectrum personality. And AS personality is associated with engineering and mathematics.
I come out as introvert on Myers-Briggs, I'm an engineer, and, whilst I enjoy social gatherings, they're tiring for me, and I often need to take 'time out' either during them, or afterwards. So I'm probably somewhere along the autistic spectrum. Well, somewhere towards the autism end; we're all
somewhere along the spectrum...
Since a lot of climbers seem to be science or engineering types, it wouldn't surprise me to find a majority are introvert. Then there's the issue of the solitary nature of climbing, versus team sports.